A Look at the New WordPress Brute Force Amplification Attack
Recently, a new brute force attack method for WordPress instances was identified by Sucuri. This latest technique allows attackers to try a large number of WordPress username and password login combinations in a single HTTP request.
The vulnerability can easily be abused by a simple script to try a significant number of username and password combinations with a relatively small number of HTTP requests. The following diagram shows a 4-fold increase in login attempts to HTTP requests, but this can trivially be expanded to a thousand logins.
This form of brute force attack is harder to detect, since you won’t necessarily see a flood of requests. Fortunately, all CloudFlare paid customers have the option to enable a Web Application Firewall ruleset to stop this new attack method.
What is XML-RPC?
To understand the vulnerability, it’s important to understand the basics of the XML remote procedure protocol (XML-RPC).
XML-RPC uses XML encoding over HTTP to provide a remote procedure call protocol. It’s commonly used to execute various functions in a WordPress instance for APIs and other automated tasks. Requests that modify, manipulate, or view data using XML-RPC require user credentials with sufficient permissions.
Here is an example that requests a list Continue reading